Such a lens is a semi-finished product, from which subsequently a spectacle lens is cut out and fitted into a spectacle frame, for example by an optician.
Methods for producing a lens by casting are known for example from U.S. Pat. No. 4,251,474 and WO 02/087861. In this production method, a monomer is cast into a cavity bounded by two molding shells and a seal and is polymerised therein, so that in doing so the lens is created. The seal is then removed and the lens is separated from the two molding shells. The lens can then be provided with optical layers, e.g. with antireflection layers, anti-scratch layers etc, in immersion baths or in a vacuum-coating installation such as a PECVD installation.
The cast lenses mostly have a protruding projection along their circumference which is brittle and can therefore easily be damaged. In order to ensure that detached splinters do not reach the optical surface of the lens during the subsequent coating by means of a process in which the layers are applied in a vacuum-coating installation, the lenses need to be cleaned in one or several washing processes prior to placement in the vacuum chamber.